On Tue, 10 Sep 2013, Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> wrote: > If branch device advertise dummy enough sink, bail out early > trusting to sink count instead of falling back to ddc probe > which is deemed to fail. > > References: https://bugs.freedesktop.org/show_bug.cgi?id=60263 > Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_dp.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c > index 8c70a83..703767e 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -2786,9 +2786,15 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp) > if (!(dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT)) > return connector_status_connected; > > + /* Analog or other */ > +#define DP_PORT_TYPE_DUMMY 0x2 > + > /* If we're HPD-aware, SINK_COUNT changes dynamically */ > hpd = !!(intel_dp->downstream_ports[0] & DP_DS_PORT_HPD); > - if (hpd) { > + > + /* ...and if the downstream port type is dummy enough > + * dont fall into ddc probe as it will fail */ > + if (hpd || dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_PORT_TYPE_DUMMY) { > uint8_t reg; > if (!intel_dp_aux_native_read_retry(intel_dp, DP_SINK_COUNT, > ®, 1)) I only started really looking into the patch, and the DP spec, now that I tricked you into submitting it to the ml... thanks for the patch, but I'm afraid this isn't the right thing to do. :/ The original comment above, "If we're HPD-aware, SINK_COUNT changes dynamically", is correct, but misleading. AFAICT we can, and should, just always read SINK_COUNT on branch devices. It should work, but it only changes dynamically for HPD capable devices. Further, the original code checks for HPD in ->downstream_ports, but that's only available (and initialized!) if DPCD rev is > 0x10. That's not checked. Fixing this doesn't give us full support for branch devices, but would be a baby step forward. Want to do it or shall I? Cheers, Jani. _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
